The Securities and Exchange Commission has decided to file a civil complaint against the brokerage firm First Jersey Securities Inc. over its trading in a small oil and gas exploration firm, an SEC lawyer revealed in federal court here today.

The complaint has not been filed, however, pending the outcome of a court battle over the disappearance of some First Jersey files and documents from an SEC hearing room. First Jersey, blaming the loss on the government, wants the SEC actions halted until they are recovered.

While neither SEC officials in Washington nor commission attorneys here would comment on the nature of the complaint against First Jersey, a sworn affidavit filed with the court in October said SEC investigators would recommend that civil injunctive action be taken against the firm and its president, Robert E. Brennan, under the general antifraud provisions of the securities law.

Brennan has denied that his firm has violated securities laws.

In his affidavit, SEC Special Trial Counsel Ralph Pernick said First Jersey and Brennan are alleged to have violated the security law's general antifraud section and a rule pertaining to stock manipulation.

The civil injunctive action the commission voted to seek on Wednesday against First Jersey involves trading in the stock of Geosearch, an oil and gas exploration firm. Such injunctive action is the agency's prime means of enforcing security laws designed to protect investors.

With the complaint, the SEC asks a federal court to order that the alleged violations be stopped. If the court upholds the SEC complaint after a trial, any future violations become a matter of criminal contempt of the court order. The court also can order some punishment -- generally a fine -- beyond forcing an end to illegal practices.

According to SEC Assistant General Counsel Richard M. Humes, the SEC planned to file its complaint against First Jersey next Thursday -- the day after a court-sanctioned ban on public SEC action against First Jersey was scheduled to end.

Humes' announcement surprised U.S. District Judge H. Lee Sarokin, who expected to hear arguments today on First Jersey's motion for temporary restraining order barring the SEC from continuing its seven-year-long investigation of the fast-growing brokerage firm [and its more recent probe] involving Geosearch, whose stock trades over the counter. First Jersey requested the injunction on the grounds that the missing files are vital to its defense.

The judge said that, after reading briefs in the case, his "tentative inclination" was to deny the First Jersey motion because the company had failed to exhaust its administrative remedies before the SEC.

The commission's action Wednesday placed the case in a new light, Sarokin said, and he withheld any decision until 4 p.m. on Dec. 13. Meanwhile, SEC attorneys agreed that they would not file its complaint until Sarokin rules.

First Jersey Attorney Donald A. Robinson called the commission's action against the security firm in the Geosearch case "shocking" and said it showed there was no chance the SEC would agree that the disapearance of the files made it impossible for First Jersey to defend itself against the SEC charges.

He told Sarokin that, if the SEC commissioners would not accept his argument opposing a complaint in the Geosearch case, they are unlikely to do so in the fuller investigation before them. "We presented to them our best shot" on the missing files in a five-page letter to the commission, Robinson said.

But SEC attorney Humes said it was still unclear whether the government could replace the missing files in the Geosearch case with its own investigative transcripts and records. Moreover, Humes said, First Jersey could advance its argument as part of its defense that the SEC lost files vital to its case.

Robinson said merely filing a civil complaint would cause irreparable harm to First Jersey because of unfavorable publicity. Humes said First Jersey first mentioned the Geosearch case in seeking the temporary restraining order, and the "public interest" has to be considered.